USMLE Forum Archives - USMLE Step 1 - Biochemistry Question
Biochemistry Question
riya10 - 02-19-11 16:34
if the prevalence of pyloric stenosis is approxi 1/1,000 for females and 1/200 for males, then how it is possible that the average affected female has to be located higher on the liability disrtibution than is an affected male.
riya10 - 02-19-11 16:34
if the prevalence of pyloric stenosis is approxi 1/1,000 for females and 1/200 for males, then how it is possible that the average affected female has to be located higher on the liability disrtibution than is an affected male.
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#5
Re: Biochemistry Question
riya10 - 02-26-11 16:13 i don,t think so......can anybody explain me?????
#8
Re: Biochemistry Question gulrezm - 03-03-11 14:03 because the disease occurs more rarely in females...when it DOES happen in females it's usually a more serious disease...
I think this is the right explanation hopefully it makes sense...
basically females are more protected from the disease...so when the disease gets so bad that it breaks this barrier...it is expressed in females. Thus it's a more serious illness in females and has higher liability
#9
Re: Biochemistry Question babbu5508 - 03-03-11 14:15 hmm.. id dont think so...because the question is not asking about the severity of the disease probably...it says "average affected female has to be located higher on the liability disrtibution than is an affected male."
#10
Re: Biochemistry Question riya10 - 03-03-11 17:31 think again, it doesn't suit with question........
#12
Re: Biochemistry Question gulrezm - 03-04-11 14:02 In many multifactorial diseases the two sexes have different probabilities of being affected. For example, pyloric stenosis occurs in about 1/200 newborn males but only in about 1/1000 newborn females. This means that there is a double threshold, one for females and one for males, with the female threshold farther from the mean than that for the male. However, since it takes more deleterious genes to create an affected female, she has more genes to pass on to the next generation. Her male offspring are at a relative high risk of being affected when compared to the population risk.
#13
Re: Biochemistry Question gulrezm - 03-04-11 14:06 so because it takes more deleterious mutations in order to be expressed in the female, she is at higher risk (thus higher liabiltiy) of producing offspring with the disease. furthermore, because males are already at a higher disposition to being affected by pyloric stenosis, the disease likelihood is even more increased in male offspring in particular...
#14
Re: Biochemistry Question riya10 - 03-07-11 16:41 in our notes, its like...recurrence risk for multifactorial diseases increase if the affected individual of the less commonly affected sex will be higher on the liability distribution. therefore the average affected female is likely to be located higher on the liability distribution. the presence of more risk factors implies that the affected female's relatives are more likely to be affected than are the affected male's relatives.
#15
Re: Biochemistry Question babbu5508 - 03-19-11 17:23 
posted by gulrezm on 03-04-11 14:02
In many multifactorial diseases the two sexes have different probabilities of being affected. For example, pyloric stenosis occurs in about 1/200 newborn males but only in about 1/1000 newborn females. This means that there is a double threshold, one for females and one for males, with the female threshold farther from the mean than that for the male. However, since it takes more deleterious genes to create an affected female, she has more genes to pass on to the next generation. Her male offspring are at a relative high risk of being affected when compared to the population risk.
In many multifactorial diseases the two sexes have different probabilities of being affected. For example, pyloric stenosis occurs in about 1/200 newborn males but only in about 1/1000 newborn females. This means that there is a double threshold, one for females and one for males, with the female threshold farther from the mean than that for the male. However, since it takes more deleterious genes to create an affected female, she has more genes to pass on to the next generation. Her male offspring are at a relative high risk of being affected when compared to the population risk.
thank you for the explanation..nicely said
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